Ball Lightning

This rune effect changes the arrow skill to a spell, firing a slow-moving purple orb that pierces 100% and zaps everything it passes over for 155% weapon damage as Lightning.

This one looks much more like a Wizard skill than a Demon Hunter ability, and it requires an entirely different approach to use. As the Ball Lightning orbs are slow moving and able to zap targets multiple times, the damage dealt varies greatly depending on the monster's movement. Fast moving attackers will only take one hit, while slow or stationary enemies, or big monsters with much larger hit boxes, will often get zapped several times.

This skill is most often compared to various rune effects in Rapid Fire, but it varies quite a bit in efficiency. It does comparable damage to Rapid Fire to a single target, but for less Hatred cost, providing the target is not moving very quickly. Since Ball Lightning pierces any number of enemies, it's got a much higher potential damage output on packs of enemies.

There's also debate from players who simply don't like using this one. The slow motion, floating, magical orbs look nothing like an arrow attack, and using Ball Lightning feels like playing a slow Wizard, rather than a fast action, fast-firing Demon Hunter.